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clk: sunxi-ng: a64: force select PLL_MIPI in TCON0 mux 

TCON0's source clock can be fed from either PLL_MIPI, or PLL_VIDEO0(2X),
however MIPI DSI output only seems to work when PLL_MIPI is selected and
thus the choice must be hardcoded in.

Currently, this driver can't propagate rate change from N-K-M clocks
(such as PLL_MIPI) upwards. This prevents PLL_VIDEO0 from participating
in setting of the TCON0 data clock rate, limiting the precision with
which a target pixel clock can be matched.

For outputs with fixed TCON0 divider, that is DSI and LVDS, the dotclock
can deviate up to 8% off target.

Signed-off-by: Roman Beranek <me@crly.cz>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Acked-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20230505052110.67514-2-me@crly.cz
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
This commit is contained in:
Roman Beranek 2023-05-05 07:21:07 +02:00 committed by Jernej Skrabec
parent ac9a78681b
commit ca1170b699
1 changed files with 13 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/clk/sunxi-ng/ccu-sun50i-a64.c
View File

@ -528,11 +528,18 @@ static SUNXI_CCU_M_WITH_MUX_GATE(de_clk, "de", de_parents,
0x104, 0, 4, 24, 3, BIT(31),
CLK_SET_RATE_PARENT);
/*
* DSI output seems to work only when PLL_MIPI selected. Set it and prevent
* the mux from reparenting.
*/
#define SUN50I_A64_TCON0_CLK_REG 0x118
static const char * const tcon0_parents[] = { "pll-mipi", "pll-video0-2x" };
static const u8 tcon0_table[] = { 0, 2, };
static SUNXI_CCU_MUX_TABLE_WITH_GATE(tcon0_clk, "tcon0", tcon0_parents,
tcon0_table, 0x118, 24, 3, BIT(31),
CLK_SET_RATE_PARENT);
CLK_SET_RATE_PARENT |
CLK_SET_RATE_NO_REPARENT);
static const char * const tcon1_parents[] = { "pll-video0", "pll-video1" };
static const u8 tcon1_table[] = { 0, 2, };
@ -953,6 +960,11 @@ static int sun50i_a64_ccu_probe(struct platform_device *pdev)
writel(0x515, reg + SUN50I_A64_PLL_MIPI_REG);
/* Set PLL MIPI as parent for TCON0 */
val = readl(reg + SUN50I_A64_TCON0_CLK_REG);
val &= ~GENMASK(26, 24);
writel(val | (0 << 24), reg + SUN50I_A64_TCON0_CLK_REG);
ret = devm_sunxi_ccu_probe(&pdev->dev, reg, &sun50i_a64_ccu_desc);
if (ret)
return ret;